As a diffusion membrane used when manufacturing a diffusion layer member constituting an electrode of a fuel cell, an electric double layer capacitor, or the like, PTL 1 discloses a diffusion membrane containing unbaked polytetrafluoroethylene, baked polytetrafluoroethylene, and electrically-conductive substances.
PTL 2 discloses a fuel cell gas diffusion layer that is a gas diffusion layer used in a fuel cell and includes a porous member containing electrically-conductive particles and polymeric resin as major components. PTL 2 describes that the fuel cell including the gas diffusion layer operates in such a manner that: a gas humidification dew point of an anode is 65° C.; a gas humidification dew point of a cathode is 35° C.; and a cell temperature is 90° C. (paragraph 0084).